The Present Disclosure relates, generally, to adapter frames and cages utilized to receive and shield electronic modules therein, and more particularly, to adapter frame and cage assemblies that integrate heat sinks, electromagnetic interference (“EMI”) shields and the like.
The use of pluggable modules in the electronics field is growing. Pluggable modules may be used in association with ordinary, copper-based electrical systems or they may be used in association with fiber-optic systems. However, pluggable modules used in high-speed systems generate significant heat, which must be carried away from the module in order to keep its operating temperature down to a level for which it was designed. Pluggable modules are typically inserted into a shielding cage, which shields the connection between an edge card protruding from the insertion end of a module and a receptacle connector that is mounted to a printed circuit board (“PCB”). The shielding cage is mounted to the PCB and forms a hollow space that envelops the receptacle connector. To remove the heat, the industry has adopted the use of heat sinks.
Once such heat sink is described and shown in U.S. Pat. No. 6,816,376, assigned to Tyco Electronics, wherein the shielding cage has an opening formed in its top wall, or roof. This opening permits access to the interior of the shielding cage and to the pluggable module. A terminally-conductive heat sink has a base that extends into the interior of the shielding cage and into contact with the top of the pluggable module. The heat sink is designed so that its base touches the top surface of the module and a rim that extends around the heat sink base sits on and makes contact with the shielding cage. A hold down clip is provided to maintain the heat sink in contact with the module and this clip is designed to flex in response to upward movement of the heat sink. The content of this patent is incorporated herein in its entirety.
One problem that occurs with such a structure is that either the module or the shielding cage, or both, may be manufactured out of dimension. If so, the heat sink rim separates, either partially or wholly, from contact with the shielding cage to create a gap and depending upon the severity of the misalignment, this gap may extend around the entire extent of the opening in the upper surface of the cage. Where the gap occurs between the heat sink and the cage, it defines a portal for the emanation of EMI. Designers strive to achieve the lowest possible leakage of EMI from any cage, as the EMI is prone to interfere with the transmission of signals through the module and through other electronic devices in proximity to the cage and module. Shielding cages and similarly, adapter frames, that also are intended to receive electronic modules typically have a series of holes, or penetrations, formed therein in order to provide functional features, such as engagement or insertion points and the like. These openings are relatively large in size and provide ports through which EMI may escape. In view of the high data rates that are desired by the industry, these holes have become smaller, yet they still provide a source of EMI leakage. This is because as the data rates increase, EMI can travel through smaller holes.
Additional problems occur with the use of shielding cages that are stamped and formed from sheet metal in mounting the cages to their supporting PCBs. Typically compliant or press-fit pins are stamped from the cage bottom and bent into a vertical orientation. Although received in a through-hole in the PCB and sometimes soldered thereto, the opening in the cage bottom from which the mounting pin was stamped defines an opening in the cage that is susceptible to EMI leakage. Additionally, forces generated by insertion of the module into the receiving cage/frame may be large and can impose stress and excessive loads on the compliant pins.
In view of such problems, it is therefore desirable to provide a shielding cage or adapter frame that has an EMI reduction solution associated with it, and possesses good thermal conductivity and robust mounting capabilities.